Disposable wearing article

ABSTRACT

A disposable wearing article has its outer surface formed from a nonwoven fabric of thermoplastic synthetic fibers. A tape strip constituting each of the tape fasteners is folded in Z- or inverted Z-shape and attached in such folded state to the outer surface of the wearing article by means of first adhesive. As for a spot at which the tape strip is attached to the outer surface of the wearing article, the nonwoven fabric at least partially presents a film-like outer surface.

BACKGROUND OF THE INVENTION

The present invention relates to disposable wearing articles and morepreferably to such articles provided with tape fasteners and adapted tobe suitably used as diapers or the like.

U.S. Pat. No. 4,237,890 (Citation 1) discloses a fastening means usedfor a disposable diaper comprising a tape strip folded withextendability in S- or Z-shape. This tape strip has a first end portionfixed to an outer surface of the diaper by means of firstpressure-sensitive adhesive and a second end portion opposed to thefirst end portion wherein the second end portion may be pulled to unfoldand thereby to extend the tape strip. The second end portion is coatedon its inner surface with second pressure-sensitive adhesive.

U.S. Pat. No. 5,182,156 (Citation 2) also discloses a fastening meanscomprising a tape strip folded in Z-shape. This tape fastener is used ina manner similar to that in which the tape fastener disclosed inCitation 1 is used.

Japanese Laid-Open Patent Application Gazette No. 1990-4372 (Citation 3)discloses a disposable absorbent product provided with a fastenersystem. This fastener system comprises a Y-shaped tape strip.

For the tape strip disclosed in Citation 1 and 2 normally folded in S-or Z-shape before actually used, it is likely that the tape strip mightbe easily peeled off from the outer surface of the diaper under apeeling force generated between the tape strip and the outer surface ofthe diaper as the tape strip is unfolded and extended. It will beeffective to enhance an adhesive force of the pressure-sensitiveadhesive for the purpose of preventing such peeling off of the tapestrip. However, if the tape strip having such a high adhesive force isattached to the outer surface of the diaper formed from a nonwovenfabric, texture of the nonwoven fabric, more specifically, intertwinedcomponent fibers constituting the nonwoven fabric may be disentangled asthe tape strip is pulled outward and the tape strip may fall off fromthe diaper together with these disentangled component fibers.

The Y-shaped tape strip used for the product disclosed in Citation 3 isattached to both the outer surface and the inner surface of the diaperby means of pressure-sensitive adhesive coated on this tape strip toprevent the tape strip from readily falling off from the diaper as thetape strip is pulled outward. However, depending on the design, suchY-shape tape strip generally has poor extendability compared to the tapestrip folded in S- or Z-shape.

SUMMARY OF THE INVENTION

It is an object to provide a disposable wearing article having an outersurface defined by a nonwoven fabric improved so that the fastener tapefolded in Z- or inverted Z-shape attached to the outer surface of thewearing article can be reliably prevented from falling off from thewearing article even when the tape strip is pulled outward for actualuse thereof.

The present invention is directed to a disposable wearing article havinga crotch region, a front waist region extending forward from the crotchregion and a rear waist region extending rearward from the crotchregion, each of these regions having inner and outer surfaces, a pair oftransversely opposite lateral edge portions extending in parallel toeach other in back-and-forth direction of the crotch region, the frontand rear waist regions further including respective upper end portionsextending in a transverse direction of the crotch region between thetransversely opposite lateral edge portions, and the front waist regionor the rear waist region having, on an outer surface in a vicinity ofthe lateral edge portions and/or the upper end portion, tape fastenerseach comprising a tape strip folded in Z- or inverted Z-shape withextendability and a fastening means provided on the tape strip.

The wearing article according to the present invention further comprisesthe outer surfaces of the front and rear waist regions being formed froma nonwoven fabric of thermoplastic synthetic fibers, the tape strip ofthe tape fastener having a surface thereof facing the nonwoven fabricbonded to the nonwoven fabric by means of adhesive and, in the nonwovenfabric, a spot destined to be bonded to the tape strip at leastpartially presents a film-like outer surface formed by a plurality ofthe synthetic fibers fused together.

The tape fastener for the disposable wearing article has its tape stripbonded to the nonwoven fabric defining the outer surface of the wearingarticle by means of adhesive wherein the spot at which the tape strip isbonded has been transformed to the film-like state. In this way, thereis no anxiety that the nonwoven fabric's texture might be destroyed andthe tape fastener might fall off from the wearing article as the tapefastener is forcefully pulled outward.

According to one preferred embodiment of the invention, the nonwovenfabric has a basis weight in a range of about 10 to about 50 g/m². Evenwhen the outer surface of the wearing article is formed by the nonwovenfabric having such basis weight as small as in the range of about 10 toabout 50 g/m², it is ensured to eliminate an anxiety that the nonwovenfabric's texture might be destroyed and the tape fastener might fall offfrom the wearing article.

According to another preferred embodiment of the invention, the wearingarticle is of pants-type formed by the front and rear waist region putflat and heat-sealed at spots arranged along respective lateral edgeportions and, in each of these heat-sealed spots, the synthetic fibersform the film-like outer surface and the tape strip is bonded to thisfilm-like outer surface. In the case of the wearing article according tothis embodiment, it is unnecessary to form the film-like outer surfaceby locally transforming the nonwoven fabric merely for the purpose ofattaching the tape fastener to the article. It is for the reason thatthe film-like outer surface formed when the front and rear waist regionshas been bonded to each other along the respective transversely oppositelateral edge portions may be utilized for attachment of the tapefastener.

According to still another preferred embodiment of the invention, thenonwoven fabric presents the film-like outer surface in a regiondestined to be bonded to the tape strip, at least one of this region'sends opposed as viewed in a direction in which the tape strip isunfolded and extended. According to this embodiment of the tape strip,in a region of the tape strip facing the nonwoven fabric, at least oneof this region's opposite ends may be bonded to the film-like outersurface to prevent the tape fastener from falling off from the wearingarticle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cutaway perspective view showing a typicalembodiment of a disposable wearing article (disposable diaper) accordingto the invention;

FIG. 2 is a sectional view taken along the line II-II in FIG. 1;

FIG. 3 is a view similar to FIG. 2, showing a tape fastener having beenunfolded;

FIG. 4 is a perspective view showing the used diaper having been rolledup for disposal;

FIG. 5 is a view similar to FIG. 2, showing one preferred embodiment ofthe invention; and

FIG. 6 is a partially cutaway plan view showing an open-type diaper asanother preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Details of a disposable wearing article according to the presentinvention will be more fully understood from the description givenhereunder with reference to the accompanying drawings.

FIG. 1 is a partially cutaway perspective view showing a disposablepants-type diaper 1 as a typical embodiment of the disposable wearingarticle according to the invention. The diaper 1 comprises an innersheet 2 defining an inner surface facing the wearer's skin, an outersheet 30 defining an outer surface facing the wearer's garment and aliquid-absorbent core 40 interposed between these two sheets 20, 30. Theinner sheet 20 is liquid-pervious and formed from a nonwoven fabric madeof thermoplastic synthetic fibers or perforated film made ofthermoplastic synthetic resin. The inner sheet 30 has an inner surface20 a and an outer surface 20 b. The outer sheet 30 comprises a firstouter sheet 31 formed from a nonwoven fabric of thermoplastic syntheticfibers and a liquid-impervious second outer sheet 32 formed from a filmof thermoplastic synthetic resin and intermittently bonded to the innersurface of the first outer sheet 31 by means of hot melt adhesive 2 (SeeFIG. 2). The first outer sheet 31 defines an outer surface 30 b of theouter sheet 30 and the second outer sheet 32 defines an inner surface 30a of the outer sheet 30. The core 40 is formed from well known orpublicly known absorbent material such as fluff pulp or a mixture offluff pulp and super-absorbent polymer. As for the configuration, thediaper 1 is composed of a crotch region 7, a front waist region 5extending forward from the crotch region 7 and a rear waist region 6extending rearward from the crotch region 7. FIG. 1 illustrates thediaper 1 as viewed from behind, i.e., the rear waist region 6 is seen onthis side of the front waist region 5. Respective portions of the innersheet 20 and the outer sheet 30 extending outward beyond a peripheraledge of the core 40 are put flat together and these portions of theinner sheet 20 and the second outer sheet 32 are heat-sealed oradhesively bonded to each other at bonding spots 3 arrangedintermittently in a waist-surrounding direction. Thus, transverselyopposite lateral edge portions 9 a, 9 b, 9 c of the front waist region5, the rear waist region 6 and the crotch region 7 are respectivelydefined, on one hand, and upper end portions 10 a, 10 b of the front andrear waist regions 5, 6 are respectively defined, on the other hand. Thetransversely opposite lateral edge portions 8 a of the front waistregion 5 and the transversely opposite lateral edge portions 9 b of therear waist region 6 are put flat and bonded together at bonding spots 15arranged intermittently in vertical direction of the diaper 1 so as toform a waist-hole 11. At the same time, these transversely oppositelateral edge portions 9 a, 9 b bonded together in this manner cooperatewith the crotch region 7 to form a pair of leg-holes 12. Alongrespective peripheral portions of these waist-hole 11 and leg-holes 12,a plurality of waist-surrounding elastic members 13 and a plurality ofleg-surrounding elastic members 14 are interposed between the innersheet 20 and the outer sheet 30 and bonded in stretched state to theinner surface of at least one of these sheets 20, 30. Tape fasteners 16are attached to the transversely opposite lateral edge portions 9 b ofthe rear waist region 6, respectively. These tape fasteners 16 are usedto put the front and rear waist regions 5, 6 in close contact with thewearer's waist and/or to hold the used diaper 1 in rolled up state fordisposal (See FIG. 4).

FIG. 2 is a sectional view taken along the line II-II in FIG. 1. Thetape fastener 16 is adapted to be folded in Z- or inverted Z-shape asviewed in the waist-surrounding direction before actually used and, inFIG. 2, the tape fastener 16 is illustrated to be folded in Z-shape. Thetape fastener 16 is unfolded and extended in its longitudinal directionas the tape fastener 16 is pulled leftward as viewed in FIG. 1, i.e.,outward from the associated marginal portion 9 b as indicated by anarrow A with a finger-grip 52 c held between the fingers (See FIG. 3).

Referring to FIG. 2, the tape fastener 16 comprises a tape strip 50 andfastening means. The tape strip 50 has an inner surface m destined toface the first outer sheet 31 in the unfolded/extended state and anouter surface n opposed to the inner surface m. In the state folded inZ-shape as shown by FIG. 2, the tape strip 50 has a first tape section51 facing the first outer sheet 31, a second tape section 52 includingthe finger-grip 52 c and a third tape section 53 extending between thefirst tape section 51 and the second tape section 52. The first tapesection 51 has a surface facing the first outer sheet 31 bonded over itswhole area to this first outer sheet 31 by means of first adhesive 61.The first tape section 51 has an inner end portion 51 a lying asidetoward a center line P-P (See FIG. 1) bisecting a width of the diaper 1and an outer end portion 51 b opposed to the inner end portion 51 a,i.e., lying aside toward the associated marginal portion 9 b. The secondtape section 52 has an inner end portion 52 a lying aside toward thecenter line P-P and an outer end portion 52 b lying aside toward theassociated marginal portion 9 b. The finger-grip 52 c is contiguous to adistal end of the outer end portion 52 b. The third tape section 53 hasan inner end portion 53 a being contiguous to the inner end portion 52 aof the second tape section 52 and an outer end portion 53 b which iscontiguous to the outer end portion 51 b of the first tape section 51.The second tape section 52 is coated on its inner surface m facing thethird tape section 53 except the finger-grip 52 c and the inner surfacem of the inner end portion 52 a with second pressure-sensitive adhesive62 functioning as fastening means. The second tape section 52 istemporarily bonded to the inner surface m of the third tape section 53by means of the second pressure-sensitive adhesive 62. Of the outersurface n of the third tape section 53 facing the first tape section 51,the outer surface n of the inner end portion 53 a is coated with thirdpressure-sensitive adhesive 63 by means of which the third tape section53 is temporarily bonded to the outer surface n of the inner end portion51 a of the first tape section 51.

Referring to FIG. 2, the bonding spots 15 at which the front and rearwaist regions 5, 6 are bonded to each other along the transverselyopposite lateral edge portions 9 a, 9 b, respectively, may be heatedunder a pressure or sonic welded to fuse the inner sheet 20, the firstouter sheet 31 and the second outer sheet 32 together into asingle-layer film at the respective bonding spots 15. At these spots 15,a plurality of component thermoplastic synthetic fibers havingconstituted nonwoven fabric layers in the inner sheet 20 and the firstouter sheet 31, respectively, have no more fibrous form which otherwisecould be separated into individual component fibers. The first adhesive61 serves for permanently bonding the first tape section 51 to the firstouter sheet 31 and, by means of this first adhesive 61, the first tapesection 51 is bonded not only to the nonwoven fabric in the first outersheet 31 but also to the bonding spots 15 presenting film-like state.

FIG. 3 is a view similar to FIG. 2, showing the tape fastener 16 havingbeen unfolded and extended in the direction indicated by the arrow A.Force intending to peel the outer end portion 51 b of the first tapesection 51 off from the first outer sheet 31 in the transverselymarginal portion 9 b is generated between these outer end portion 31 andfirst outer sheet 31 as the tape fastener 16 is pulled in the directionof the arrow A. However, it is unlikely that the tape fastener 16 mightfall off from the diaper 1 even if the tape fastener is forcefullypulled because the first tape section 51 has its outer end portion 51 bbonded to the spots 15 presenting film-like outer surfaces by means ofthe first adhesive 61. Now it is assumed that the first tape section 51is placed more aside toward the center line P-P than in the illustratedembodiment and bonded to the nonwoven fabric zone of the first outersheet 31 but not to the spots 15. In this case, texture of the nonwovenfabric may be destroyed as the tape fastener 16 is forcefully pulled. Inother words, the intertwined component fibers constituting the nonwovenfabric and being in contact with the first adhesive 61 may bedisentangled and plucked off from the nonwoven fabric zone until thetape fastener 16 may fall off from the diaper 1. Such problem is due toa fact that an adhesive strength between the first adhesive 61 and thosefibers is sufficiently high to disentangled the intertwined componentfibers constituting the outer sheet 31. The problem can not be solvedmerely by adjusting the adhesive strength provided by the first adhesive61 but it is rather preferred to make such adjustment, if necessary,only after the first tape section 51 has been bonded to the bondingspots 15.

FIG. 4 is a perspective view showing the used diaper 1 having beenrolled up for disposal. The tape fastener 16 is adapted to be unfoldedfrom the state in FIG. 3 with the finger-grip 52 held by the fingers andthen to be fixed to a selected position on the diaper 1 by means of thesecond adhesive 62. Utilizing such feature, it is preferred to fastenthe diaper 1 in its rolled up state with the tape fasteners 16immediately after the diaper 1 has been used, as illustrated. The tapefastener 16 is useful also to pick up any slack of the diaper 1 in thewaist-surrounding direction appearing after the diaper 1 has been put onthe wearer. Specifically, the tape fastener 16 may be extended in thewaist-surrounding direction so as to tuck the diaper 1 and thereby topick up the slack. The second adhesive 62 is used in this manner notonly as a fastening means but also as a means to keep the tape fastener16 in Z-shape as seen in FIG. 2. Therefore, an adhesive force of thesecond adhesive 62 may be adjusted so as to achieve these intendedpurposes. For example, an adhesive force of the second adhesive 62 usedfor the purpose as illustrated by FIG. 4 may be sufficiently high toallow the tape fastener 16 to be permanently bonded to a target spot orappropriately low to allow the tape fastener 16 to be temporarily bondedto the target spot. Referring to FIG. 2, the inner surface m of thethird tape section 53 facing the second adhesive 62 may be previouslycoated with suitable surface treatment to facilitate the second adhesive62 to be peeled off.

FIG. 5 is a view similar to FIG. 2, showing one preferred embodiment ofthe invention. In this embodiment, a tape strip 50 constituting each oftape fasteners 16 for diaper 1 comprises three separate tape strips,i.e., a first tape section 51, a second tape section 52 and a third tapesection 53. An outer end portion 51 b of the first tape section 51 isfolded back and permanently bonded to an outer end portion 53 b of thethird tape section 53 by means of first adhesive 61. An inner endportion 53 a of the third tape section 53 is temporarily bonded to aninner end portion 51 a of the first tape section 51 by means of thirdadhesive 63, on one hand, and partially folded back and permanentlybonded to an inner end portion 52 a of the second tape section 52 bymeans of fourth adhesive 64, on the other hand. The outer end portion 53b of the third tape section 53 further extends outward to define adistal end portion 53 c which extends, in turn, beyond the outer endportion 51 b of the first tape section 51 and is permanently bonded tobonding spots 15 having film-like outer surface by means of fifthadhesive 65. The inner end portion 51 a of the first tape section 51 ispermanently bonded to a film-like spot 68 formed on the first outersheet 31 by means of first adhesive 61. The film-like spot 68 refers toa portion of the nonwoven fabric constituting the first outer sheet 31which has been transformed to the film-like state in the substantiallysame manner as in the case of the bonding spots 15. More specifically,the inner sheet 20, the first outer sheet 31 and the second outer sheet32 may be heated under a pressure or sonic sealed to fuse these sheets20, 31, 32 together. There is no anxiety that component fibers of thefirst outer sheet 31 might be plucked off by the first adhesive 61 aswell as the fifth adhesive 65 and the tape fastener 16 might fall offfrom the diaper 1 as the tape fastener 16 is pulled even when both thefirst adhesive 61 and the fifth adhesive 65 have a relatively highadhesive force. As illustrated in FIGS. 2 and 5, in a region of the tapestrip 50 facing the first outer sheet 31, at least one of this region'sends opposed in the waist-surrounding direction is preferably bonded tothe first outer sheet 31 at the film-like spot 68.

FIG. 6 is a partially cutaway plan view showing an open-type diaper 101as another preferred embodiment of the invention. The diaper 101comprises a liquid-pervious inner sheet 20 formed from a nonwoven fabricof thermoplastic synthetic fibers, a substantially liquid-imperviousouter sheet 30 formed from a nonwoven fabric of thermoplastic syntheticfibers and a liquid-absorbent core 40 interposed between these twosheets 20, 30. As for the configuration, the diaper 101 is composed of acrotch region 7, a front waist region 5 extending forward from thecrotch region 7 and a rear waist region 6 extending rearward from thecrotch region 7. Transversely opposite lateral edge portions 9 b of therear waist region 6 and a transversely middle spot of the rear waistregion 6 in the vicinity of its upper end portion 10 b are provided withthe tape fasteners 16 similar to those used in the embodimentillustrated by FIG. 2, respectively. These tape fasteners 16 are adaptedto be unfolded and thereby to be extended outward from the diaper 101 asindicated by imaginary lines by pulling these tape fasteners 16 withrespective finger-grips 52 c. Spots of the outer sheet 30 defined insiderespective imaginary lines 71 are heated under a pressure so thatnonwoven fabric of the outer sheet 30 in these regions may betransformed to a film-like state. The tape fasteners 16 are bonded tothese regions by means of the first adhesive 61 (See FIG. 2) andtherefore it is not apprehended that texture of the outer sheet 30 mightbe destroyed and the tape fasteners 16 might fall off from the diaper101 even when the tape fasteners 16 are forcefully pulled. When the tapefastener 16 is attached to the rear waist region 6 in the vicinity ofits upper end portion 10 b, the inner and outer sheets 20, 30 may bewelded to each other continuously or intermittently along the upper endportion 10 b between the transversely opposite lateral edge portions 9 bto ensure that the outer sheet 30 is locally transformed to thefilm-like state, and thereafter the tape fastener 16 may be bonded tothe film-like spot obtained in this manner.

Without departing from the scope of the present invention, the firstouter sheet 31 comprising a nonwoven fabric used in the embodiment shownby FIG. 2 as well as the outer sheet 30 used in the embodiment shown byFIG. 6 may be transformed to the film-like state in any spots so far asthese spots are to be provided with the tape fasteners. The fasteningmeans formed by the first adhesive in the embodiments having beendescribed heretofore may be replaced by a hook member, one of componentsconstituting together with a loop member so-called mechanical fastener,which is adapted to be anchored on the nonwoven fabric forming the firstouter sheet 31. When this hook member is used as the fastening means,the outer surface n of the third tape section 53 shown in FIG. 2 isformed preferably using a nonwoven fabric so that the second tapesection 52 can be temporarily fixed to the outer surface n of the thirdtape section 53. The present invention is applicable not only to thedisposable diaper having been described heretofore but also to the otherwearing articles such as training pants and pants for incontinentpatient.

The present invention makes it possible to mass-produce the wearingarticle free from the anxiety that the tape fasteners might fall offfrom the article.

1. A disposable wearing article comprising: a crotch region; a frontwaist region extending forward from said crotch region; and a rear waistregion extending rearward from said crotch region, each of said regionshaving inner and outer surfaces, a pair of transversely opposite lateraledge portions extending in parallel to each other in back-and-forthdirection of said crotch region, said front and rear waist regionsfurther including respective upper end portions extending in atransverse direction of said crotch region between said transverselyopposite lateral edge portions, and said front waist region or said rearwaist region having, on said outer surface in a vicinity of said lateraledge portions and/or said upper end portion, tape fasteners eachcomprising a tape strip folded in Z- or inverted Z-shape withextendability and a fastening means provided on said tape strip, saiddisposable wearing article further comprising: said outer surfaces ofsaid front and rear waist regions being formed from a nonwoven fabricmade of thermoplastic synthetic fibers; said tape strip of said tapefastener having a surface thereof facing said nonwoven fabric bonded tosaid nonwoven fabric by means of adhesive; and in said nonwoven fabric,a spot destined to be bonded to said tape strip at least partiallypresents film-like outer surface formed from a plurality of saidsynthetic fibers fused together.
 2. The wearing article according toclaim 1, wherein said nonwoven fabric has a basis weight in a range ofabout 10 to about 50 g/m2.
 3. The wearing article according to claim 1,wherein said wearing article is of pants-type formed by said front andrear waist region put flat and heat-sealed at spots arranged alongrespective lateral edge portions and, in each of these heat-sealedspots, said synthetic fibers form said film-like outer surface and saidtape strip is bonded to this film-like outer surface.
 4. The wearingarticle according to claim 1, wherein said nonwoven fabric presents, ina region destined to be bonded to said tape strip, at least one of thisregion's ends opposed as viewed in a direction in which said tape stripis unfolded and extended, said film-like outer surface.